1. Field of the Invention
The present invention relates to a method for providing a location service and a mobile terminal and, more particularly, to a method for determining an optimum positioning method, selecting an appropriate map, and indicating the location of a mobile terminal on the map to provide a location service, and a mobile terminal.
2. Related Art
A mobile terminal, such as a cellular phone, a PDA, a smartphone, or the like, is able to determine its location according to various positioning methods. Currently, a positioning method of a terminal providing the widest service area and high accuracy is a global navigation satellite system (GNSS).
For example, a particular terminal may determine its location by using satellite signals received from at least four or more GNSS satellites by using a GNSS receiver in an outer area in which satellite signals of GNSS satellites can be received. The positioning by using GNSS offers high accuracy and availability within 10 m in a flatland or in the suburb in which a direct line of sight is secured between the GNSS satellites and the terminal, but in a downtown congestion area, a non-line of sight area, there is a location error up to 50 m due to a multi-path error, and in particular, in an indoor area, a reception signal sensitivity is degraded, making it impossible to determine the location of the terminal.
The difficulties in providing the location information in the indoor area and in downtown congestion area can be resolved by a positioning method based on a wireless communication infrastructure. For example, a particular terminal may determine its location in an indoor environment in which multiple WLAN APs (Wireless Local Area Network Access Points) are installed, based on measurement information such as a received signal strength indicator (RSSI) received by a WLAN reception unit, a round trip time (RTT), or the like . . . . In another example, a certain terminal may determine its location through a positioning method such as an enhanced cell/sector, advanced forward link trilateration (AFLT), enhanced observed time difference (EOTD), observed time difference of arrival (OTDOA), or the like, by using identification information of a mobile communication base station and a time difference of arrival (TDOA) measurement value.
In an indoor/outdoor transition section, the accuracy of a terminal's location can be improved through a composite positioning method based on multiple sensors whose error characteristics are complementary.
For example, when a terminal including a GNSS and a WLAN receiver moves to an indoor area from an outdoor area, GNSS location accuracy is degraded due to a reduction in the number of visible satellites and an increase in a multi-path error resulting from the entry of a building, while a WLAN-based location accuracy can be improved owing to an increase in the number of reception-available WLAN APs and an increase in the received signal strength. Meanwhile, when the terminal moves from an indoor area to an outdoor area, the GNSS location accuracy and the WLAN location accuracy have the opposite characteristics. Thus, the accuracy of a final location of the terminal can be improved by combining location sensors having the complementary location error and distribution characteristics.
Despite the presence of various terminal positions methods, it is not easy to provide continuous and accurate location information of a terminal in both indoor and outdoor areas through a single positioning method.
In the related art, the location of a terminal is determined by selecting a single positioning method having a minimum location error range among available positioning resources after determining whether or not positioning resources from a wireless communication infrastructure such as a mobile communication base station, WLAN, Bluetooth™, UWB (Ultra-wideband), RFID (Radio-Frequency Identification), or the like, or from the GNSS have been received.